I've been playing around with some chromatic chord progressions recently but I am having a hard time analyzing the changes and figuring out the key for melody/soloing purposes. How do you know which chords are the passing chords and which are the diatonic ones?

For example, something like:

F#m - F - Esus2 - E♭m7♭5 - Dmaj7

My first instinct would call it D Major E Major because the half diminished E♭ (or in this case D#) makes sense as a vii chord. But it could also be F# minor with the D being the VI. To my ear, F# minor pentatonic seems to work, but not perfectly. Can I even use just one scale/mode for the whole melody, or do need to I change the scale with each chord change?

When you have such special chord progressions, with chromatic based melody, the key is neither major or minor, but something completely different (may not even follow any official scale pattern).
– aweDec 17 '14 at 11:44

2 Answers
2

It's difficult to tell which are the passing chords from your example because there's no time values. Passing chords are of short duration and/or occur on off-beats.

So absent that, I would look at the chord tones for each to determine what melody to play.

F#m: F# A C# ("color tones": E G# B D)

F: F A C ("color tones": E G Bb D)

Esus2: E B F#

Ebm7b5: Eb Gb(F#) Bbb(A) Db(C#)

Dmaj7: D F# A C# ("color tones": E G B)

(The "color tones" are known by a number of names, including "chord extensions" and are the natural or altered 7th, 9th, 11th and 13th notes above the chord triad of 1 (b)3 5.)

An easy way to choose melodies based on note sets is to look for good motion between the note sets. I would use scalar/chromatic moves, arpeggios, interval jumps and ornaments, looking forward and backward on the chord progressions.

So for example, I might choose a basic melody skeleton and add fleshy bits to something like:

F# F E D# D

for a chromatic motion or

F# C F# A D

for something a little more angular and more solidly in D major.

Sometimes thinking in terms of chords and key centers works best and sometimes thinking in terms of sets of notes works best. It's a subtle distinction but an important one.

It is possible to have multiple keys in a song. Charles Mingus in 'Nostalgia in Times Square' changed 3 keys in as many bars. He used chromatic notes in the melody as well. So, don't try to narrow your progression down to only one possible key.

Now, let's say you are in D major:

F#m -> 3rd chord of the scale.

F -> chromatic. The bass goes F# to F(natural) to E.

Esus2 -> 2nd chord of the scale.

E♭m7♭5 -> Chromatic (of some kind). If it was Eb7, it would be a tritone substitution of the dominant chord of your scale (the dominant is A7 and you substitute it with Eb7) which is a really common substitution. But it is not. So, it could be the 2nd chord of the D Phrygian mode. But we are not in D Phrygian mode. It could also be the 2nd chord of the Db minor scale. But we are not in Db minor scale.

Dmaj7 -> 1st chord of your scale.

So, your progression could work on the D major scale, with an addition of a few notes if you want the chromatics to be pointed out.